Shadows in the Labyrinth
by unrequit3d
Summary: A crossover between the following series: The Heroes of Olympus, The Kane Chronicles, Harry Potter, The Mortal Instruments, and more? What will happen when the Labyrinth (from PJO) reappears, and mysterious villains resurrect to challenge the heroes once again? Can our protagonists unite, as Hera once again schemes to save the world?
1. Chapter 1 (PJO)

When Heroes meet

Hey readers! Thanks for your interest in this fanfic I hope you'll enjoy it. I'll be including characters from The Heroes of Olympus, The Mortal Instruments, and Harry Potter. I'll be switching POVs per every chapter, or possibly more than once per chapter, but it will depend on what makes the most sense. Updating will be slow, as I have school and homework to deal with, but we'll see. Thanks for bearing with me.

Chapter 1: Morning commute, Macy's, and Monsters

Percy

So there we were, five demigods walking through New York City's sidewalks at morning rush hour. Annabeth, Jason, Piper, and Nico and I bumped through a flood of mortal commuters, being jostled about as the crowd streamed through.

Nico winced as a commuter accidentally clipped him with his briefcase, screaming into a Bluetooth headset as he did. "Gods, I think ghouls in the Underworld have more manners than this."

Jason glanced at Piper, and grimaced, as if he'd tasted something sour. "Uh, you might be wrong there. Remember that incident with Antinous and his suitor army? That didn't go so well. For them, I mean."

I grinned, remembering Jason's encounter with ex-Praetor Michael Varus, who had gone over to Gaea after his death. "Yeah, I remember. How was it being an old man Grace?"

"Well, mainly it sucked. I think Hazel outdid herself there." Jason made a face.

Annabeth rolled her storm-gray eyes in exasperation. "Yes, well if you boys are done, I think we're almost at the Heroes Counsel. The map only goes so far, so we'll be relying on our own navigation from here on."

I glanced over her shoulder at the street map she held aloft. "Hey Wise Girl, I thought you just updated most of Cabin 6's maps and scrolls. How come this one dosen't cover as much ground?"

Annabeth frowned thoughtfully, her brow furrowing. "I could have sworn on the Styx that I had changed this one as well. It could be that the meeting's location is unplottable. It might not show up on maps. A GPS or other digital guides would go haywire."

 _Just like Ogygia_ , I thought. Immediately I felt a surge of guilt as I remembered the island, and its prisoner.

Just then, Piper's eyes widened. "Guys! I see something over there in that department store!"

Jason groaned, and I echoed the sentiment. "If it's clothes shopping time, I'll be outside."

Before I could add my support and approval to the newly formed "I hate clothes shopping club", Nico spoke up, startling the rest of us He'd stayed quiet for most of the trip, silently shadowing the main group.

"I think Piper's right about that. There's a blue glow in that "Macy's" over there. I'm afraid it might be a-"

"An entrance to the Labyrinth." Annabeth muttered a Greek curse. "Of course. The gods would make us go into that place again. Naturally."

Piper shrugged. "Well, as long as we don't meet Medea under there, I'm in for a little shopping trip! Hopefully it's tamer now, and easier to navigate."

Jason smiled wryly, addressing the group "I think that in all of our questing experiences, the most dangerous way is usually the right way to head. And that's worked out okay so far, seeing as we're all still alive."

I nodded in answer. "Now, shall we go shopping? I haven't had my dangerous near-death experience of the day." We drew our weapons, and stepped through the glass sliding doors.

 **-** Sorry for the short chapter, I'm getting off the ground with this story so hopefully from now on they'll be at least a thousand words. I will also switch to a 3rd person perspective to better fit the writing styles of the source material. - _unrequited_


	2. Chapter 2 (HP)

Ch. 2

Harry

"Are we nearly there?" Ron asked for what had to be the thirtieth time that morning.

"No Ron, for the last time, we are not there yet!" Harry and Hermione chorused.

The three had set out from King's Cross station on the muggle underground that morning, and had been traveling for around an half an hour. Ron had never traveled on the subway before, and Harry and Hermione had a good laugh at his fascination with the turnstiles, as well as the train itself.

"What a weird way to travel! What will muggles think of next?" He would exclaim. Eventually though, the novelty wore off, and Ron became somewhat impatient with the long journey.

Harry opened his pocket, reading over the letter from Professor McGonagall. On their latest visit to Hogwarts as alumni, she instructed the three of them to attend a meeting, where the most powerful witches and wizards would give a presentation.

"Yeah, I reckon it's not on the map. That's odd." Ron scratched his head. "So, is it nearly our stop?" He asked, grinning sheepishly at Hermione.

Hermione looked up, checking the electronic station display. "Oh! This is the station we want!" She seized her beaded handbag (enchanted to carry much more than usual), and sprinted to the doors, folding back the map and letter as she went.

Harry and Ron hurried after her, barely managing to slide through the automatic doors before the subway continued on its way. Hermione stood on the platform, looking around at the exits leading up to the streets.

"This is where we're meant to go." Hermione looked around. "I wonder why this stop isn't busy. It's the morning rush hour; this place should be full of commuters."

Ron surprised both Harry and Hermione by chiming in with a suggestion. "Maybe this meeting place is hidden! Like Hogwarts, this place can't be approached by muggles, they won't see it!"

Just then, the lights went out, plunging the station into darkness. There was only one light left on, leading to an elevator door set in one of the support pillars. It reminded Harry of the entrance to Platform 9¾ at King's Cross station.

"Bloody hell." Ron muttered nervously. "I can't see a damn thing. Lumos!"

The others followed suit, muttering "Lumos", and lighting up their wands, illuminating their surroundings. The stairs leading up to the city had also disappeared, and panels slid over the openings, blocking the outside light from entering. The three explored the room, finding no exits or passages other than the elevator panel. The darkness was very off-putting, and the silence created an eerie atmosphere.

Ron suggested that they could easily blast apart the panels to the stairs with Reductor curses, but Hermione worried that the powerful explosion might destabilize the supports, raining debris down on their heads. Also, Harry suspected that the wizards conducting the meeting might have set this trap as a test, or insurance that muggles that somehow got past the anti-muggle charms couldn't enter.

"There's no putting it off. We're going to have to get in that elevator." Ron exclaimed, after 10 minutes of searching. "That elevator is the only way to go."

Harry and Hermione agreed, though all of them were reluctant. They approached the doors, and entered the elevator. The elevator was much more technologically advanced than it looked from the exterior, with futuristic, clean white paneling. The doors slid shut behind them, with an ominous clang. The three waited, wands at the ready as the elevator made its descent.

The trio stood somewhat awkwardly as the elevator music played. Mostly for something to do, Harry checked the electronic display. It indicated that they were going straight down, despite never pressing any buttons for floors. There seemed to be 12 floors, and they had only passed 4. "This is the place on the map. We shouldn't face any opposition if we're talking to friends here, but just in case... we should be prepared for a fight." The others nodded, tersely.

The elevator reached the 12th floor with an annoyingly cheerful 'ding'. The three peered into the brightly light room, forgetting all about potential threats. The room, if you could call it just a room, featured a large outdoor gazebo, constructed of large pillars of white stone supporting a concentric roof, with an oculus*.

The underside of the roof displayed tiled mosaic, mainly showing the same 12 figures doing battle, which were illuminated by the light spilling in from the oculus. The light gave them the illusion of movement as the sun sparkled off of the tiny multi-colored rocks set in the mosaic. A nearby garden brimmed with vitality, lush vegetation growing, even underground. Animals inhabited the garden, and Harry could make out a peacock strutting around. A stream gurgled, branching off into a man-made spiral pattern on the floor, which was also made of the white stone. 20 chairs surrounded a round table, with a gilded throne of gold presiding over the space, as well as the same white stone, maybe marble.

The three stood on the edge of the elevator door, entranced. Harry wondered how the sunlight managed to shine so brightly so far down, and how the plants grew, but he had seen far stranger things caused by magic before. There was a sort of gravity about this place. Hermione was leafing furiously through a Latin to English dictionary; whispering under her breath so fast that Harry could only make out a few broken words, like "Greek", "Gods", and "Queen". She must have retrieved the book from her purple beaded handbag, which was charmed to contain many warehouses worth of supplies and stored items.

"Blimey, this place is beautiful." Ron said as he gazed around the room, transfixed. The others nodded in agreement, stepping fully into the room.

In fact, the three were so distracted by the wonders around them, that they didn't even notice the group of teenagers that had been silently observing them from a shadowy corner. There were 4 of them, all dressed in non-descript black clothing with strange tattoo-like markings scattered across most of their visible skin.

Harry first noticed a rather short girl with red hair who studied them curiously, but suspiciously. She stood close to a tall, fair-haired boy who surveyed them with a raised eyebrow and a sarcastic smile. Next to them was a tall girl with flowing black hair who gave them a teasing wink, but then laughed and turned away; and finally a tall, pale, boy with brown hair that stared around the room anxiously; not focusing on anything particular. It was as if he hadn't noticed their entry, but Harry thought he could see the boy's eyes flicker towards them occasionally.

"Well, you're late," The blonde boy drawled. "That is, if you're even the Idris ambassadors that we're supposed to meet, and not some _mundanes_ that came in here by accident."

Hey guys! So, I managed to get out another chapter pretty quickly (hooray!) and hopefully I can keep updating at this pace! Thank you so much to the 3 followers so far (currently... hopefully we can get more) for your interest, and please share your thoughts with me if you enjoyed it and want to share your opinion with me.

So once again, thanks for reading, and have a great day!

P.S. As a side note, I think I spend way too much time on background information, description of characters and developing settings, but I like descriptive writing when I read, and I want to create specific images as a backdrop to stories. Thanks for bearing with me! *I am referring to an architectural oculus, which is a circular hole in a roof used as a natural light source. Not Oculus Rift, the VR headset.


	3. Chapter 3 (MI)

Chapter 3: Pancakes, Plans, and Plot Advancement

Clary

Clary blinked groggily as shafts of golden sunlight swept across the Institute bedroom. She groaned, rolling over and burying her face in the pillow.

"C'mon Fray, rise and shine." Simon tapped her shoulder. Compared to the warmth of her covers and the pleasant sunlight, his hands were like ice. The jolting sensation sent a shock wave through her body.

Clary shrieked indignantly and rolled off the bed to escape him. "Ack! Simon, why's your hand so freezing?"

Simon crouched next to Clary, sprawled on the floor in a heap, thoroughly entangled in her blanket. He was wearing a worn sweater, dark jeans, and a faded t-shirt. "Probably because I just helped Jace grab some frozen blueberries for his pancakes. Izzy wanted to make breakfast, but he insisted. Everyone did, really. Last time she made something, she gave Alec indigestion for a week."

"You're her boyfriend; you're supposed to support her. I hope you didn't diss her cooking, Lewis." Clary got to her feet, disentangling herself from the blanket cocoon.

"I protested along with her when Jace said that he'd make it instead, but it was a fake sort of protest. You know when someone says they'll do the dishes and you protest, and they insist but you really didn't want to do it anyways? It was that kind of protest." Simon bent to retrieve the blanket pile. "Anyways, Alec sent me to wake you up. He said you better get ready for the visit to the Silent City and that we're heading out after breakfast."

Clary grabbed some clothes and headed towards the attached bathroom. "Alright fine, let him know I'm coming. Just gonna change first."

"Okay, got it. I'll save you a plate of pancakes."

As Simon disappeared, Clary eyed herself in the mirror. Her hair was a mess, and seemed to be flat on one side where she'd slept on it. Thankfully it wasn't too tangled. She viciously attacked her bed head with a comb, quickly got changed and went downstairs. The enticing scent of fresh, delicious pancakes wafted through the kitchen door, reminding Clary how famished she was. Walking through the doorway, Clary was reminded of how distinctly modern the Lightwood's kitchen was, especially when compared to the rest of the Institute. Someone had thrown open the windows, and the sunlight made the metal counters sparkle.

Looking around the kitchen, Clary saw Simon, Isabelle, and Alec at the table. Simon waved at her when she came in, but Isabelle and Alec were too preoccupied to notice her arrival. Isabelle was hunched over, clutching Simon's DS and occasionally prodding it with the stylus. From the familiar stirring motions Isabelle was making, Simon seemed to be teaching her how to play "Cooking Mama". The two sat next to one another, with their heads together to better see the small screen. As for Alec, he sat across from them, engrossed in his phone. Jace stood next to the red cast iron stove, staring critically at a container of baking soda. Clary walked over to Jace, who was now showing off; deftly balancing a stack of plates in his right hand, and casually flicking his spatula to flip pancakes with the other, all while he consulted Mayrse's cookbook. He was dressed in an odd mix of heavy Shadowhunter gear and an old pajama shirt. "Hey bloodsucker, more coming up." Jace set down the plates and gesticulated in Simon's direction.

Simon looked up from the game, disgruntled. "You haven't called me bloodsucker for a while now. I was starting to hope you'd abandoned your insulting nickname shtick."

Jace grinned devilishly. "Well, I can't call you 'mundane' anymore, and Clary seems to think that both 'weasel face' and 'rat boy' are insensitive. So it'll have to be bloodsucker until I can think up something more or equally insulting." He turned around to face Clary. Isn't that right?"

Clary sighed in mock disapproval. "Well, if you must. I still don't see what's wrong with just calling him Simon." She pointed to the finished pancakes, cutting off Jace's incoming rebut. "Simon doesn't have to come over here, I can just grab those."

Jace handed her the full plate as well as a basket of toppings (maple syrup, butter, whipped cream, and strawberries). "And here I was hoping that we'd have an engaging debate all morning about what I can call him from now on. What happened to you, Fray? You used to be fun."

Clary set the plate down and took a seat next to Alec. She speared several pancakes onto her own plate, added syrup and started wolfing them down. "You can be fun. I choose not to be hungry." She replied, muffled by a mouthful of dough. The pancakes were a perfect golden brown, and tasted soft and fluffy, yet crispy on the outside. She spooned some blueberries onto her plate.

"Jace, these are delicious!" Isabelle proclaimed, clapping her hands; Jace's stark refusal to eat her cooking seemingly forgotten. She nibbled delicately on a whipped cream-laden pancake sprinkled with blueberries to punctuate her words. Simon looked over her plate with a forlorn glance. He had retrieved a bottle of blood from the fridge and heated it up in the microwave, now sipping from it glumly through a straw while he continued to poke at the DS' buttons.

Jace slid into a seat next to Clary. He wiggled his eyebrows at Simon. "Bet you wish you could taste these, don't you Simon?"

Simon frowned slightly. "To be honest, I do. As much as I hate to admit it, those do look good. Wait…" He tilted his head and smiled in triumph. "You called me Simon!"

Jace nodded, but Clary saw the tiny upturn at the corner of his lip that most people wouldn't have noticed or thought much of. She Jace knew well enough to see that on the inside, Jace was gleeful at something. Simon must have walked into some sort of verbal trap. "Ah, but Simon, you know I hate to redundantly state what is obvious. Look at yourself. Why would I need to call you a bloodsucker again? You seem to have embraced it." He pointed a long, graceful finger at Simon's straw.

Simon looked down, and deflated. "Thought I had you there." He said ruefully. Isabelle giggled, and Simon ruffled her hair in response.

Alec reached across Clary for the whipped cream, giving the canister a hard shake.

Jace rested his arm on the back of his chair, leaning forward conversationally. "So, Alec. How's Magnus doing? I would assume you and he have had quite the exchange over the past 20 minutes you've been staring at that phone."

Alec rolled his eyes. "Stuff it, Jace." I haven't been texting Magnus, I've been checking up on the mundane news. Strange stuff has been happening. In fact, Maryse said they might send us in to investigate some of the claims."

Jace groaned. "Alec, this sort of thing never turns out to be real. Anything even slightly out of the ordinary is paranormal activity to mundies. They just love to imagine magic and supernatural beings everywhere. Hell, they believe that a fairy leaves them money and collects their baby teeth. Besides, why do we have to investigate? Shouldn't they send a team from the Clave?"

"We're the only ones left in New York. Don't you remember? Everyone is gone for the meeting at Idris. Besides, some of the rumors don't sound like the usual mundie hocus pocus. Dark clouds and strange lightning gathering around the Empire State?" Alec shook his head as if to clear it. He looked genuinely troubled.

Just then the Institute phone rang. The sound reverberated through the hallways.

Alec started, then got up to pick up the call. A few minutes later he returned, with gear in hand. "The Clave called. They need us to take a trip to the Silent City. Apparently, we're supposed to meet some Idris ambassadors."

Isabelle pushed back her chair, springing to her feet. "Wait. Alec, why do we need to gear up just to meet with some people from the Clave?"

Alec frowned. "I was wondering that myself. The woman on the other line was quite specific. Maybe you'll be going to investigate after meeting with them? I'm not entirely sure." He turned to Simon. "That reminds me. You'll be going too. The Idris ambassadors need to speak with you as well."

Simon waved his hands in protest. "But I thought the Silent City is where your dead are kept. Where those monk dudes keep the deepest darkest secrets of you Shadowhunters. Isn't it sacrilege or something for a vampire to go in?"

Alec shrugged. "I'm not sure. But what the Clave wants, the Clave

generally gets. I'll have to stay back and watch the Institute so it'll be you four."

Pancakes forgotten, everyone dispersed. Clary helped Simon gear up, and they met Isabelle and Jace at the Institute doors.


End file.
